A liquid crystal display device and a semiconductor device are formed of a plurality of layers patterned on a substrate. A plurality of processes is carried out for forming and patterning the layers on the substrate. And, generally, various methods, such as a chemical vapor deposition method, a sputtering method, a photoresist method, and so on, are used for such processes. However, since a large number of layers are required to be formed on the substrate, productivity may be decreased if the fabrication process is complicated. Therefore, it is necessary to adopt a simple fabrication process in case mass production is desired.
A related art printing nozzle will now be described in detail with reference to the accompanying drawings.
FIG. 1A illustrates a cross-sectional view of a related art printing device. And, FIG. 1B illustrates a process of coating a printing material onto a printing roll by using the related art printing device.
Referring to FIG. 1A, the related art printing device includes a main body 10 and a nozzle unit 20, which is formed on a lower portion of the main body 10. The main body 10 includes an accommodation groove 15 for accommodating (or containing) a printing material. The nozzle unit 20 includes a slit 25 that is connected to the accommodation groove 15 of the main body. The slit 25 allows the printing material to flow out in order to perform coating.
Referring to FIG. 1B, the printing material 30 contained in the accommodation groove 15 of the main body 10 flows out through the slit 25 of the nozzle unit 20. A layer of the printing material 30 is then coated on a printing roll 40, which rotates below the printing device. At this point, since the related art printing device includes one nozzle unit 20 formed on the lower portion of the main body 10, the amount of printing material 30 flowing out of the printing device cannot be controlled or regulated.
In FIG. 1B, a thickness of the layer of printing material 30 that is coated onto the printing roll 40 may be controlled by controlling or regulating the amount of printing material 30 flowing out of the printing device. However, since the amount of the printing material itself cannot be controlled, as described above, the thickness of the coating layer may be controlled by adequately adjusting the rotation speed of the printing roll 40.
Yet, there is a limitation in adjusting the thickness of the coating layer by simply controlling the rotation speed of the printing roll 40. Most particularly, when the printing material 30 is to be coated to a thickness that cannot be controlled by adjusting the rotation speed of the printing roll 40, the printing roll 40 must be rotated several times, which extends the fabrication process time. Moreover, if a flat printing plate is to be coated instead of the printing roll 40, shown in FIG. 1B, either the printing plate or the printing device should make repeated back-and-forth movements, thereby preventing the printing material from being coated at a uniform thickness.